Project description:Microalgal biomass is a promising feedstock for biofuels, feed/food and biomaterials. However, while production and commercialization of single-product commodities is still not economically viable, obtaining multiple products in a biomass biorefinery faces several techno- economic challenges. The aim of this study was to identify a suitable source of hydrolytic enzymes for algal biomass saccharification. Screening of twenty-six fungal isolates for secreted enzymes activity on Chlamydomonas reinhardtii biomass resulted in the identification of Aspergillus niger IB-34 as a candidate strain. Solid state fermentation on wheat bran produced the most active enzyme preparations. From sixty-five proteins identified by LC-MS, the majority corresponded to predicted secreted proteins belonging to the Gene Ontology categories of catalytic activity/hydrolase activity on glycosyl and O-glycosyl compounds. Defatted biomass of the more biotechnologically relevant strains towards the production of commodities, Chlorella sorokiniana and Scenedesmus obliquus, was fully saccharified after a mild pretreatment at 80 °C for 10 min, at a high biomass load of 10 % (w/v). Deffated and 2 saccharified biomass of both strains was further converted into ethanol by fermentation with Saccharomyces cerevisiae at a theoretical maximum efficiency, either by separated or simultaneous sccharification and fermentation. The resulting insoluble protein after biomass defatting with an organic solvent and enzymatic saccharification resulted in a high digestibility in an in vitro digestion assay. Proof-of-concept is presented for an enzyme-assisted biomass biorefinery which recovered 81% of the main biomass fractions in a likely active form for the conversion of lipids and carbohydrates into biofuels and proteins into feed/food.
Project description:The functional diversity of soil microbial communities was explored for a poplar plantation, which was treated solely with biogas slurry, or combined with biochar at different fertilization intensities over several years.
Project description:Biogas plants (BGPs) produce methane and carbon dioxide through the anaerobic digestion of agricultural waste. Identification of strategies for more stable biogas plant operation and increased biogas yields require better knowledge about the individual degradation steps and the interactions within the microbial communities. The metaprotein profiles of ten agricultural BGPs and one laboratory reactor were investigated using a metaproteomics pipeline. Fractionation of samples using SDS-PAGE was combined with a high resolution Orbitrap mass spectrometer, metagenome sequences specific for BGPs, and the MetaProteomeAnalyzer software. This enabled us to achieve a high coverage of the metaproteome of the BGP microbial communities. The investigation revealed approx. 17,000 protein groups (metaproteins), covering the majority of the expected metabolic networks of the biogas process such as hydrolysis, transport, fermentation processes, amino acid metabolism, methanogenesis and bacterial C1-metabolism. Biological functions could be linked with the taxonomic composition. Two different types of BGPs were classified by the abundance of the acetoclastic methanogenesis and by abundance of enzymes implicating syntrophic acetate oxidation. Linking of the identified metaproteins with the process steps of the Anaerobic Digestion Model 1 proved the main model assumptions but indicated also some improvements such as considering syntrophic acetate oxidation. Beside the syntrophic interactions, the microbial communities in BGPs are also shaped by competition for substrates and host-phage interactions causing cell lysis. In particular, larger amounts of Bacteriophages for the bacterial families Bacillaceae, Enterobacteriaceae and Clostridiaceae, exceeding the cell number of the Bacteria by approximately four-fold. In contrast, less Bacteriophages were found for Archaea, but more CRISPR proteins were detected. On the one hand, the virus induced turnover of biomass might cause slow degradation of complex biomass in BGP. On the other hand, the lysis of bacterial cells allows cycling of essential nutrients.
Project description:In this study, centrifugal fractionation has been applied for fractionation of two biogas sludge samples to analyze proteins extracted from (i) crude fibers, (ii) suspended microorganisms, and (iii) secreted proteins in the supernatant using a gel-based approach followed by LC-MS/MS identification.
Project description:Abiotic stress is a major factor affecting the growth, development, yield and quality in plants including the important biomass yield such as in a bioenergy feedstock crops. In a first of its kind, RNA-seq based high resolution survey of abiotic stress-induced transcriptome of bioenergy feedstock model plant western poplar (Populus trichocarpa accesion Nisqually-1) was carried out by way of 81 libraries made from total RNA isolated from three tissues, mature vascular leaf, stem xylem and root sampled from plants subjected to untreated control and treated with four individual stress treatments cold, heat, drought and high salinity. For every tissue and treatment type including controls, three individual plants were used per treatment as biological replicates. This research project is supported by the DOE Office of Science, Office of Biological and Environmental Research (BER), USA, grant no. DE-SC0008570